1. Technical Field
The present invention relates to optical laser fibers and methods of using them in surgical procedures. More particularly, the present invention relates to laser fiber assemblies and methods of using them in the treatment of various surgical procedures involving emission of laser energy in order to effect deep tissue coagulation or direct ablation.
2. Background Information
Optical lasers, such as Nd:YAG lasers, are commonly used in the conduct of surgical procedures. One advantage of laser surgery is that it can often be performed through a relatively small incision or by insertion into an existing body passageway. Laser surgical procedures can frequently be performed on an out-patient basis, resulting in significantly lower cost and less inconvenience to the patient. Dramatic shortening in recovery time is often seen in comparison to traditional surgery which it replaces. For these reasons, substantial effort and expense are being directed toward the development of new laser apparatus and improved methods of surgical treatment using medical lasers.
Various configurations of optical fibers have been developed for different types of surgical procedures. One particularly useful configuration involves contact laser surgery, wherein the tip of an optical fiber assembly is brought into direct contact with tissue desired to be removed, thereby causing it to be cut or vaporized, hereinafter referred to as "ablation". Sometimes, however, ablation is not the most effective means for dealing with a medical problem. Accordingly, an alternative optical fiber assembly often referred to as a "side-firing" fiber has found applications in a variety of situations not readily susceptible to treatment by direct ablation.
A typical side-firing laser optical fiber utilizes a mirror or other optical surface to reflect a laser beam traveling down a fiber so as to emerge from the tip of the fiber at a selected angle. The laser beam is then directed from a short distance onto tissue to be treated. The effect of this treatment is deep tissue coagulation and subsequent tissue necrosis which ultimately results in sloughing off of treated tissue.
One use for which side-firing fibers is currently being tested is in connection with the treatment of benign prostatitis hyperplasia, often referred to as "BPH" for purposes of brevity. BPH is a condition involving an enlarged prostate gland, typically increasing between about two and four times normal size. This condition occurs in approximately one-third of all males over age 60. Currently, approximately 400,000 cases are treated each year in the United States alone, and this number can be expected to increase as the population ages.
BPH is characterized by nocturia (bed-wetting), hesitancy in urination, decreased force of urinary stream, post-voiding dribbling, and a sensation of incomplete emptying. Although incontinence is the most common and emotionally disturbing complaint, it is possible for the enlargement to continue to the point of acute urinary retention. That problem is both painful and dangerous, requiring immediate treatment.
The most common treatment at the present time is known as transurethral resection of the prostate ("TURP"), which involves removal of portions of the prostate gland using a special cytoscope inserted into the urethra. Following a TURP procedure, a typical patient must wait about seven to fourteen days before resuming normal activities, and there is a high incidence of post-operative problems. For example, about 95% of TURP patients experience retrograde ejaculation. It has also been reported that it may take upward of 50 to 100 procedures for an physician to attain true skill at performing TURP procedures; one can only wonder at the fate of the first 50 to 100 patients of each such physician.
Although testing is still far from complete, initial reports indicate that laser treatment of BPH is an improvement over TURP procedures. One such procedure involves the use of side-firing fibers to direct Nd:YAG laser energy onto enlarged prostate tissue. The primary result of this treatment is deep tissue coagulation and subsequent tissue necrosis, which effects a reduction in the size of the prostate over a period of several months following the procedure as the necrotic tissue sloughs off. This technique is reported to be much easier to perform, resulting in proficiency after only five to ten procedures. It also has a much lower reported incidence of problems such as retrograde ejaculation--only about 25% of patients report that adverse side-effect. Hence, it will be appreciated that BPH looms as a major problem for which side-firing laser fibers have shown promise in treating.
Yet, side-firing fibers suffer from drawbacks which require improvement. For example, side-firing fibers are designed to be used in a non-contact mode by generating a relatively broad beam of laser energy that causes deep coagulation and subsequent tissue necrosis rather than a direct ablation of external tissue. Although this is a useful function, it has been discovered that in many procedures, such as BPH, it is often useful to be able to ablate surface tissue for immediate effect rather simply await the delayed effect caused by deep coagulation. Using current technology it is necessary to use a different fiber assembly for direct ablation than is used for deep tissue coagulation.
Another disadvantage of side-firing fibers is the lack of uniform beam intensity at all points at which the beam contacts surrounding tissue. There is also a need to carefully aim the beam at each location wherein it is desired to effect deep tissue coagulation and subsequent tissue necrosis. This requires the fiber to be rotated in order to aim the beam at surrounding tissue. Such rotation requires great care, since it is necessary to irradiate each surrounding portion of tissue for substantially the same period of time in order to insure that the desired effect is obtained. If adequate care is not taken, too much or too little deep tissue coagulation will occur, causing greater or lesser deep tissue necrosis to occur than desired.